u-boot/drivers/mtd/spi/Kconfig

config DM_SPI_FLASH
	bool "Enable Driver Model for SPI flash"
	depends on DM && SPI
	help
	  Enable driver model for SPI flash. This SPI flash interface
	  (spi_flash_probe(), spi_flash_write(), etc.) is then
	  implemented by the SPI flash uclass. There is one standard
	  SPI flash driver which knows how to probe most chips
	  supported by U-Boot. The uclass interface is defined in
	  include/spi_flash.h, but is currently fully compatible
	  with the old interface to avoid confusion and duplication
	  during the transition parent. SPI and SPI flash must be
	  enabled together (it is not possible to use driver model
	  for one and not the other).